This invention relates to tuning of parameters of a control system in which a plurality of control nodes are worked in association with one another, and, more particularly, relates to an improvement in a vehicular control system.
In recent years, each of a large number of vehicle components is mounted with a microcomputer for control (i.e., an electronic control unit, which will be referred to as an ECU hereinafter) and is operated by pieces of software installed in the ECU (as disclosed in, for example, “Development Strategy in Software Installed in Vehicle” attributed to Kenji Suganuma and Hiroyuki Murayama, on pages 363 to 368 of Vol. 44 No. 4 of Information Processing which was published by Information Processing Society of Japan in April, 2003). Although the ECU operates by itself in many cases today, it has been demanded to allow a plurality of ECU's to organically work in association with one another to bring more sophisticated operations to realization. For instance, when a driver of a vehicle wants to go round a curve at the highest possible speed, he or she demands to apply driving forces to outer wheels and small braking forces to inner wheels while shifting the load of the vehicle inwards by means of a suspension control system.
To actualize more sophisticated functions, a vehicle performs various operations with the aid of several tens of or even a hundred ECU's. For example, the vehicle makes use of an antilock brake system (ABS), an air bag, an engine control as a measure responsive to emission regulations enacted in various countries, an engine control for achieving a more favorable mileage, a suspension control for suppressing shakiness in running round a curve, and the like.
The sophisticated controls as mentioned above are performed in association with a plurality of ECU's. Known as a target driving force control is, for example, to optimally control a driving torque by accelerating or decelerating a vehicle without causing a sense of discomfort to its passengers through coordination of an engine control unit, a variable-speed control unit, and the like (as disclosed in, for example, JP 2002-225590 A).
Further, a feedback apparatus for adjusting parameters of a control target is known as a unit for making an optimal gain adjustment for a plurality of control systems (as disclosed in, for example, JP 2003-65135 A).
Still further, it is also known to hierarchize a software configuration in an apparatus for synthetically controlling a plurality of actuators of a vehicle on the basis of information on a driver's operation, a state of the vehicle, information on an environment, and the like, optimize the hierarchized configuration, and thus reduce the man-hour required in the development of software (as disclosed in, for example, JP 2003-191774 A).